The present invention relates to a new and improved profile measurement control or control apparatus for a gear measuring or testing machine.
In its more particular aspects, the profile measurement control of the present development is of the type comprising a pivotable lever for infinitely controlling the direction and the speed of a drive motor for driving a generating slide or carriage carrying a generating straight edge at which a base circle disc coupled to the test specimen and pressed against the generating straight edge by a feed carriage or slide may roll without slipping. There are also provided an incremental angle transmitter coupled to the base circle disc and a measuring and recording means or device including a recording chart and recording chart feed means comprising a stepping or indexing motor which is controlled by the incremental angle transmitter. The recording chart is advanced as a function of the movement of the generating slide or carriage and in correspondence to a diagram length translation ratio or translation which is pre-selected by means of an encoding switch.
In the following, reference is made to FIG. 1 to explain the conventional measurement of a gear tooth profile. There is depicted therein a gear measuring or testing machine which enables series measurements or testing of such gear tooth profiles. A test or workpiece 1, the gear to be tested, is seated upon a rotatable mandrel or spindle 2. Secured to the same mandrel 2 is a base circle disc 3, the radius of which corresponds to the radius of the base circle of the test specimen 1. The base circle disc 3 is pressed against a generating straight edge 5 by means of a feed carriage or slide 4 and which straight edge 5 is secured to a generating carriage or slide 6. When the generating carriage or slide 6 moves in the direction of the indicated arrow, then the base circle disc 3 rolls without slipping upon the generating straight edge 5 against which it bears under spring pressure. During this rolling movement the edge of a feeler or sensor 8 which is arranged at a sensor or measuring slide 7 is resiliently pressed against the tooth flank to be inspected of the test specimen 1. The edge of the feeler or sensor 8 is, then, located exactly above the edge of the generating straight edge 5. If the flank profile of the gear tooth is involute-shaped, the feeler 8 remains in its position. However, if there exist deviations from the involute shape, then the feeler 8 will be laterally deflected by the amount of such deviation. The feeler deflections are processed by an electronic measuring and recording device 9 and recorded on a suitable diagram or chart paper 10.
By means of a gear measuring machine or tester of such kind the measurements should be carried out at as high a measuring speed as possible (i.e. at as high a rolling speed as possible). The measuring or testing speed, however, is limited by the maximum possible recording speed (i.e. by the maximum possible paper feed rate) of the measuring and recording device 9 as will be considered in more detail further below.
The measuring or testing movements are controlled by actuating one single lever 12. The lever 12 is mounted at the control console of the gear measuring or testing machine at a location which is readily accessible for the operator. The actuation lever 12 may be pivoted in four directions (of which only 2 are shown for better clarity in FIG. 1). By such adjustment the direction of movement may be selected and the speed of the measuring carriage or slide (either the generating carriage or slide 6 or the vertical carriage or slide 11) may be adjusted continuously or infinitely from 0 to maximum speed. After the test specimen 1 including the associated base circle disc 3 has been mounted in the gear measuring or testing machine and after the feeler 8 has been positioned manually into the starting position for performing the testing or measurement work, the operator moves the lever 12 from the starting position into a stop abutting position in which the rolling speed will be maximum. The gear measuring or testing machine, however, can be operated at maximum rolling speed only if this is compatible with the maximum possible paper feed rate. For further illustration of this problem, reference is additionally made to FIG. 2 which shows the conventional profile measuring control arrangement in solid lines (and the profile measurement control device 13 according to the invention in broken or phantom lines).
The pivotable actuation lever 12 acts on the slider or movable tap SP1 of a potentiometer P1 and thereby changes the voltage tapped-off therefrom by means of which the drive motor 16" of the generating carriage 6 is controlled. This drive motor 16" moves the generating straight edge 5 which, then, sets the base circle disc 3 into rotation. The rotation of the base circle disc 3 is detected by an incremental angle transmitter 15 supplying pulses which are proportional to the angle of rotation thereof and by means of which a stepping or indexing motor 16' is controlled which is contained in the measuring and recording device 9 and which effects the paper feed. Additionally, there is provided a device or means 17 for preselecting the diagram length translation ratio or translation and which acts upon the paper feed motor 16' and affects the number of pulses supplied thereto per unit of time in such a way that the paper is truly advanced according to the scale selected by the diagram length translation in correspondence to the measuring movements of the feeler.
The path of the lever 12 for adjusting the rolling speed is affected by the radius of the base circle disc 3 selected and by the selected diagram length translation. If a smaller gear is measured or tested and thus, a smaller base circle disc 3 is used, then the rotational speed of the base circle disc 3 will be increased although the speed of the generating straight edge 5 is the same. Therefore, the incremental angle transmitter 15 will deliver more pulses per unit of time, so that the stepping motor 16' executes a more extensive movement per unit of time, thus providing for a higher paper feed rate. There is, however, an optimum speed for the paper feed rate which should not be exceeded. In the case of using a smaller base circle disc 3 the lever 12, therefore, may not be adjusted so as to engage the stop. Correspondingly the same is true for the selection of the diagram length translation. Therefore, for example, the ratios 1:2, 1:1, 2:1, 4:1, 5:1, 8:1, 10:1 and 20:1 to the rotational angle may be preselected. If the ratio increases, the paper feed rate will increase. In case that the optimum value of the paper feed rate, for example, is obtained at a ratio of 4:1, the lever 12 again may not be adjusted so as to abut the stop at greater values of this ratio.
Thus, it is up to the dexterity and the feeling or "touch" of the operator how far the lever 12 may be adjusted to attain the optimum paper feed rate. This is of disadvantage in the series inspection or testing of gears of different sizes, since the operator either already will have to know the relevant position of the lever 12 or will have to find the same by trial and error. If notwithstanding the same the operator happens to move the lever 12 too far, the measuring and recording device 9 will simply stop recording because the maximum possible paper feed rate is exceeded. Such a profile measuring method, therefore, requires specially trained or educated operating personnel.